Distribution, Abundance, and Interspecific Associations of Typhlodromips sessor (Acarina: Phytoseiidae)1

Abstract

Typhlodromips sessor DeLeon is the dominant phytoseiid in immature and unstable habitats throughout secondary succession in the Piedmont area of New Jersey. In fields approximately 1, 3, 5, and 10 years old, this mite had an average relative abundance of 95.4, 95.3, 82.8, and 72.3%, respectively. This ecological dominance was maintained in a 5-year-old field from June to October as population levels of this mite were consistently high and stable in comparison to the 13 other phytoseiid species collected there. Analysis of the 175 plant: species collected in these studies showed that T. sessor occurred in significantly greater densities upon herbaceous plants with thorny or pubescent leaves. As a general predator, T. sessor was interspecifically associated with tetranychid mites, eriophyid mites, and Thrips tabaci Lindeman. A negative association was evident between this phytoseiid and predatory phloeothripid nymphs. Geographically, T. sessor ranges from eastern Canada to Georgia and, according to Zack (1969), west to Missouri. Collection of 4584 adult phytoseiids along a transect of the east coast yielded 27 species, in which the average relative abundance of T. sessor was 89.8% in northern states, 50.7% in central states, and 0.8% in southern states.